1. Field of the Invention
The present invention relates to an air purge system capable of controlling the flow rate of air supplied around an output shaft of an electric motor.
2. Description of the Related Art
As is known in the art, there is a device for preventing impurities from entering into an electric motor housing by supplying compressed air around an output shaft of an electric motor (for example, Japanese Laid-Open Patent Publication No. 2013-236473). In the device disclosed in Japanese Laid-Open Patent Publication No. 2013-236473, an air purge device is mounted at the end surface of the housing to exhaust compressed air supplied from the outside of the air purge device toward the outer peripheral surface of the output shaft of the electric motor via a fluid path of the air purge device.
The centrifugal force and pressure around the output shaft of the electric motor change according to the rotating state of the electric motor, resulting in a change in the easiness of intrusion of impurities into the housing. However, in the device disclosed in Japanese Laid-Open Patent Publication No. 2013-236473, since the compressed air is supplied regardless of the rotating state of the electric motor, the supply amount of compressed air may be excessive or insufficient.